[Herald Interview] ‘Korea too undervaccinated to withstand delta variant’

A major theme of Korea’s health policies for the second pandemic summer is “a return of normal life.”

Political leaders and health officials promised this summer will be “closer to normal” -- business will reopen fully and people will be able to mingle more and wear masks less often.

Korea may be treading a risky path with its rush to get back to normal as the delta variant -- called “the most able and fastest and fittest” of all COVID-19 variants by the World Health Organization -- takes over as the dominant strain, says Dr. Paik Soon-young, professor emeritus at Catholic University of Korea College of Medicine’s department of microbiology.

Since its first sighting here two months ago, delta is already responsible for at least three community outbreaks in Korea. Among more than 90 countries affected by delta is the UK, whose first-dose vaccination rate is where Korea wants to be in September, at nearly 70 percent.

The delta-driven surge in some of the most well-vaccinated parts of the world serves as “a reminder that post-vaccine normal is still far off from where Korea stands,” Paik said. “Unless the right interventions are undertaken, Korea is too under-vaccinated to withstand the inevitable new variant.”

Overall, 29 percent of Korea’s 51 million people received one dose of a vaccine, according to official statistics updated Sunday, while just 9 percent are fully vaccinated.

The WHO warns delta is on course to replace alpha -- a variant initially documented in the UK -- that has been the dominant one in many parts of the northern hemisphere, including Korea’s southern port cities, for the past few months. 

Though precise estimates vary, data from Public Health England suggests delta is 60 percent more transmissible than alpha, which itself is more transmissible than the original form of the virus found in Wuhan, China.

“Korea is in an awkward phase of its vaccination campaign. More than 70 percent haven’t been vaccinated at all, and most of the people who did get vaccinated are first-dose recipients, meaning they are only partially protected,” he said.

“This is especially troubling as delta is somewhat more resistant to vaccines than other variants in circulation.”

A recent study out of the UK showed two full doses were necessary for any vaccine to provide sufficient protection against delta, Paik explained.

A single dose of either the AstraZeneca or Pfizer vaccine was only 33 percent effective at stopping symptoms from the variant, the study found. After the second dose, the AstraZeneca vaccine -- the most widely administered kind in Korea -- gave greater protection against delta at 60 percent, compared with 66 percent against alpha. The effectiveness of both doses of the Pfizer vaccine was 88 percent against delta and 93 percent against alpha.

He said the rise of delta made the exemptions from social distancing being granted to the half-vaccinated in the coming week “significantly riskier.” From July, two weeks after getting just one dose, people can socialize without limits on the size of the gathering in previously high-risk settings like restaurants. The cap on social gatherings in groups larger than five, credited for containing Korea’s deadly winter surge, is also coming loose for the vaccinated and unvaccinated alike.

“Encouraging vaccinations can be done in a way that does not jeopardize COVID-19 controls,” he said.

Paik pointed out Koreans younger than 60, the more socially active cohort, have to wait at least a couple of months before they become eligible for vaccination. “It’s almost inevitable cases will pick up among younger people who can’t get the vaccine yet,” he said.

Delta was also more likely to cause severe outcomes. One Scottish study, for instance, showed that people infected with delta were approximately twice as likely to be hospitalized as people with alpha.

Heeding health orders was crucial “now more than ever” for people who are not vaccinated yet, or half-vaccinated, he said. “The public messaging has to pivot from all the normal we will get to enjoy this summer to ‘don’t let your guard down until more of us are vaccinated.’”

Adding to worries was a delta sublineage called delta plus that may be capable of dodging vaccine-induced immunity to a greater extent, he said.

What makes some forms of the virus more efficient than others at infecting people and spreading from person to person is not always clearly explicable, he said. One explanation is that when mutations occur in the spike proteins of the virus, which bind to receptors on human cells, the virus could enter the human body more easily. That was the case with delta plus.

“Delta plus carries a mutation that is also present in the beta variant first spotted in South Africa,” he said. Earlier this year, South Africa suspended the use of the AstraZeneca vaccine after a study found it was only 10 percent protective against mild and moderate infections from the beta variant prevalent there.

“Because of the vaccine-evasive property, beta was thought to be more worrisome than alpha at first,” he said. “Months later, alpha ended up being the one that is most widespread worldwide. Travel patterns also play a role, but the point is that it’s not always easy to predict how a virus will behave in the real world.”

The good news is that there are real-world signs the vaccines are shielding people from variants, he said. In the UK, the case rates among older people, group with the highest vaccination coverage, remained low. In Korea, too, the death rates have fallen to 0.36 percent this month from 1.97 percent during its worst wave, which is largely attributable to vaccinations of vulnerable populations.

Still, the proportion of fully vaccinated people in the country aged 75 and up stood at 68 percent, leaving the rest at risk, he said. Nearly all 60- to 74-year-olds, who are now being offered their first doses of the AstraZeneca vaccine, have to wait until late August or September before they can get their second doses and attain maximum protection. 

Paik said the most urgent task facing Korea was obvious -- to get the vaccines to as many people as possible, and soon, and to bolster monitoring.

Korea is lagging behind in genomic sequencing, he said, referring to the process by which variants are identified from a pool of positive samples. The country sequences about 15 percent of all cases each week and has so far found more than 2,200 cases that involved key variants such as alpha and delta. Alpha accounts for 84 percent of known variant cases, delta 9 percent.

Officially, there are 190 patients with delta and 66 people who are categorized as their “close contact.” But variant cases in Korea are likely to be “vastly undercounted,” according to Paik.

“We are not doing enough genomic sequencing,” he said. “Ideally we should be doing 40 to 50 percent of total samples.”

He accused health officials of “downplaying” the concerns over the delta variant.

The Ministry of Health and Welfare’s spokesperson Son Young-rae said as recently as Thursday that there was “no evidence delta is any more resistant to vaccines than other variants.”

“Not much is known about the delta variant -- nothing so far that calls for additional measures at the border or within the country,” Son said, defending the easing of social distancing and travel restrictions coming into force in a few days.

“Countries such as the UK and Israel that have the highest vaccination rates anywhere are seeing a renewed surge from the variant,” Paik said. “Korea may be doing well in terms of patient numbers, at around 500 to 600 a day, but that could change as delta comes into play.

“The more we don’t know, the more careful we want to be. But we seem to be doing the opposite.”

By Kim Arin (arin@heraldcorp.com)